Peter M. Groen / oletools

(1) Cannot open a temp file for writing from 2 python processes
    simultaneously
(2) Need proper environment setup for Popen (thanks to metatoaster's
    reply on stackoverflow https://stackoverflow.com/a/72845540/4405656)
(3) Need different os-separator, so replace hard-coded '/' with
    os.path.join or os.sep
(4) Minor cleanup of imports & whitespace in test_issue_*.py

There are still 2 tests that should be adapted to Windows, but those are
lower-prio in my eyes.

Also, unittest run on my windows VM creates many resource warnings due to
non-closed file descriptors. Should address that some (future) day.

Fix unittests

Some samples triggered antivirus engines, issues #215 and #217 ended with
the agreement to encapsulate problematic samples in encrypted zip
containers and decrypt them on-the-fly. Initial support for this was added
but that did not cover 5 tests. Create on-the-fly decryption for these
tests as well and re-enable them.

Before using log_helper in olevba logged a "finalization message", which is
no longer required. Had forgotten to update unittests.

Oleobj preserve file extension

Files provided by decalage2

On my test VM this reduces test time for this one test from 33s to
10s

VBA stomping warning might occur here

Do not need the last meta-information return code json output from
olevba any more

With the creation of ftguess oleid has been changed a lot, the output
of its .check() method is very different. Instead of just adapting the
existing unittests, I re-created the complete test, trying to make it
easier to change/extend in the future.

File was created by myself, free to use

…porary workaround for #398), corresponding test files are now zipped with password 'infected-test' (for #215)

test-cases: add support for encrypted corpus